A hybrid vehicle includes an engine and an electric motor, and is capable of running with the engine or the electric motor or capable of running by the cooperation between the engine and the electric motor. For example, Patent Literature 1 proposes a hybrid vehicle configured to optimize the fuel consumption of the engine and the state of charge (hereinafter, referred to as SOC) of the battery when the vehicle runs by the cooperation between the engine and the electric motor. Note that, in the below description, the state in which the vehicle runs by the cooperation between the engine and the electric motor will be referred to as “the electric motor assists the engine.”